There has been a bit of controversy about what transmissions came from Ford in '57. The following is direct from Ford.

"According to the '57 shop manual Ford used 4 different transmissions in 1957. All the conventional (non O/D) trannys were side access covers that had the straight bottom edge to the cover. These trannys had different ratios for different engine displacements, with the lowest 1st gear ratios for the smallest engines.

Note: The tail shaft housing was different for T-birds.

The overdrives were different. The pass cars had the 6 bolt top loader tranny with a Borg Warner 3 pinion OD unit. This tranny had a 3 bolt front bearing and throw out bearing snout. All the others had 4 bolt snouts. The T Birds had what clearly are T-85 Borg Warner trannys with the curved bottom cover and the 4 pinion R-11 overdrive unit. The ratios varied in the same way as above but the ratios are different. What a parts nightmare and pretty unimportant these days."